SharePoint Tidbits - Table/Database locks - What causes these locks

Hello All,

Depending on which database and table we are locking on there several possible causes, and I want to list out these possible reasons for you.

1. If we don’t schedule the crawls properly, they could interfere with each other and cause locks on our search databases.
2. If we have large lists or libraries then a user who enumerates it could cause us to retrieve more than 5000 items which would cause a lock on the content database
3. If the any database or it’s logs need to grow, then during that time the database would lock
4. Poor performance in SQL server could cause any database to lock
   1. Memory contention
   2. CPU starvation
   3. Poor disk performance
   4. MAXDOP not being set properly could cause locks on any database (Performance issue)
   5. Overlapping process accessing a single database ie Backup, Crawl, Users, Antivirus, or any other 3^rd party app.
   6. Admins accessing database with T-SQL query that doesn’t use ‘No lock’
   7. A single workflow could cause a lock on the database
   8. Deep Site/List Hierarchy could cause a lock on the content  database
   9. Certain web parts could cause locks on the content database if used in certain ways.

I have not listed all the outliers that could cause a lock on a database but they would be a variation of what I have listed here at the root of it.